Understanding BMI when it comes to your fitness goals

WE come in all shapes and sizes, which means that there is no one healthy weight that we should aspire to on the fitness journey. This often leads to our obsession with the numbers that we see when we get on the scale. And while these numbers serve their purpose, on their own they do not paint a true picture of your physical health or fitness, says personal trainer and fitness instructor Gisel Harrow. Instead, she says that you can get a better idea of where you stand by learning your body mass index (BMI).

“Body mass index is an equation used to measure body fat. Your BMI is calculated by your weight in kilograms divided by your height in metres squared. From this calculation, you get a score, which shows you where you sit on the weight spectrum,” Harrow explained.

She pointed out that BMI is categorised into four ranges — underweight or low, normal or healthy weight, overweight or high, and then there is obesity.

“A BMI range below 18.5 is considered low and is generally associated with some nutritional challenges such as anorexia and malnutrition, while a normal or healthy weight BMI ranges between 18.5 and 24.9. If your BMI is over 25 but less than 30 then you are considered overweight. Anywhere in excess of 30, the person is considered obese,” Harrow explained.

While the BMI serves its intended purpose of measuring obesity and providing a guide for health care practitioners to treat with patients who are at risk of obesity-related diseases, Harrow warns against using BMI as your main health indicator for the simple reason that it only measures your weight versus your height and as such does not take into account the source of your weight, whether it’s from lean tissue or fat. As such, she says that this isn’t always an accurate representation of your overall health.

“What eventually happens is that someone who is at a normal body weight, but is carrying a high percentage of body fat, may be mistaken as being healthy. However, in people such as athletes, fitness fanatics or even people who simply stick to a stable fitness routine, they tend to have a greater portion of muscles than fat, and the BMI index may register them as overweight or even obese. This, therefore, means that muscular, but otherwise healthy people may be flagged as being at an increased risk for obesity-related diseases,” Harrow underscored.

It is therefore important that as you work to achieve your fitness goals, that you don’t become obsessed with your BMI. Harrow recommends that for the best assessment of your weight and health, you consider a holistic approach. So in addition to the body mass index, you should be completing certain measurements such as your waist measurement based on your gender, and collating the number of inches and pounds that you have lost, instead of just looking at an overall weight loss. If you want a precise measurement of your healthy body fat level you may look into getting a professional body fat measurement.

“So while knowing your BMI is important, especially at the start of your fitness journey, you shouldn’t focus on it alone as you progress towards your fitness goals. Just remain committed to your journey, continue to eat balanced meals, and do your usual check-ups with the doctor. Chances are he/she will tell you that there is nothing to worry about,” Harrow advised.